Why must utilities upgrade high-voltage power lines?

EXPLAIN IT TO ME

March 10, 2010|-- Jenna Portnoy

Q: PPL says its $510 million plan to string a 500-kilovolt line from its Susquehanna nuclear power plant in Luzerne County to Roseland, N.J., will keep the lights on well into the future. But the region hasn't experienced power blackouts so why should the infrastructure change?

A: The short answer is prevention.

Improperly trimmed trees in northern Ohio triggered a series of failures that led to the cascading blackouts of 2003. The outage extended throughout New York, New England and into Canada and highlighted weaknesses in the system that Congress tried to address with the 2005 Energy Policy Act.

The legislation empowered the federal government to approve new power transmission towers if states and regional groups failed to build enough lines. It also made standards set by the North American Electric Reliability Corp. mandatory.

It's those standards that the PJM, the regional transmission authority that manages the electricity grid in 13 states and the District of Columbia, uses to predict where problems could occur up to 15 years into the future.

Sophisticated computer modeling first alerted PJM to the need for expanded power in 2007, according to Paul McGlynn, the general manager for system planning. Studies in 2008 and 2009 confirmed the findings.

McGlynn likes to compare power lines to a highway system with a two-lane road crossing the Delaware from Pennsylvania to New Jersey and back. Congestion and traffic jams can clog the system, keeping people from getting where they need to go. The roads can only handle so much traffic before they need to be expanded or upgraded. The same goes for electricity and its transmission lines.

Many factors go into predicting future conditions, but changes in usage (such as more housing developments) and energy generation (solar parks) are keys. The experts at PJM identified 24 individual spots on transmission lines where problems could occur in 2012 if no action were taken.

The problem lines are located closer to Philadelphia and scattered through New Jersey, but because the whole grid is interconnected, small deficiencies could lead to cascading outages like what happened in New York a few years ago.

PJM looks at lots of potential fixes, including incremental upgrades. But eventually the existing equipment simply cannot accommodate the usage and a higher capacity line is needed, as is the case with the Susquehanna-Roseland line, he said.

''Eventually it doesn't make sense to do underlying upgrades to some facilities,'' McGlynn said. ''The system got to the point where we had to do a fairly robust upgrade.''